1weasel

: a small animal that has a thin body and brown fur and that eats small birds and other animals

: a dishonest person who cannot be trusted

pluralweasels

Full Definition of WEASEL

1

or pluralweasel: any of various small slender active carnivorous mammals (genus Mustela of the family Mustelidae, the weasel family) that are able to prey on animals (as rabbits) larger than themselves, are mostly brown with white or yellowish underparts, and in northern forms turn white in winter — compare ermine 1a

2

: a light self-propelled tracked vehicle built either for traveling over snow, ice, or sand or as an amphibious vehicle